Free running draw chuck

ABSTRACT

Free running draw chuck device for use in a lathe permitting rotation of an elongated, relatively fine workpiece or mandrel at high speeds under tension without deviation or &#39;&#39;&#39;&#39;whipping.&#39;&#39;&#39;&#39; Use of the device in formation of fine, wire reinforced catheters is shown.

mam States Patent [72] Inventor James H. Donachy [50] Field of Search279/1 R, l Wheaton,Md. A;82/1.4,3l,34,38;2l4/l.l [2]] Appl. No. 16,89422 Filed Mar. 5, 1970 1 References Cited [45] Patented Dec. 7, 1971FOREIGN PATENTS 1 Assignee The United of America as 1 18,676 9/1958U.S.S.R. 82/1 .4

represented by the Secretary of the Department of Health, Education andPmnary Examiner-Andrew R. Juhasz welfare Asslsmnt Examiner-James F. CoanAttorney-Holman & Stern 54 FREE RUNNING DRAW CHUCK 1 ABSTRACT: Freerunning draw chuck device for use in a 7 Claims, 3 Drawing Figs.

lathe permlmng rotatlon of an elongated, relauvely fine work [52] US. Cl279/ l R, piece or mandrel at high speeds under tension without devia.82/38 tion or whipping." Use of the device in formation of fine, [51 IntCl 1323b 5/00 wire i f d catheters is Shown r M 4p 54 60 a 44 i 1 34 '14RR Y5B c go so 7 fir.

M- 40 so u, '12 51 10 piece between the headstock and the tailstock andfor rotating the workpiece during a machining process. However, it isquite difficult to provide for rotation of a workpiece which isrelatively thin and elongated, providing the same with greatflexibility, since such a workpiece, in order to preclude oscillation orwhipping" due to its flexibility, when rotated at high speeds, must bemaintained under'substantial tension. The maintenance of tension on theworkpiece causes difficulty in providing rotation. The device of theinstant inventive concept is a free running draw chuck which permitsrotation of the workpiece, even at relatively high speeds, while theworkpiece is maintained under high tension between its ends.

The need for a device of the type with which the instant invention isconcerned is particularly critical in the production of dimensionallyaccurate catheters for biomedical use, where such catheters must have anextremely fine internal diameter.

Thus, the device of this invention is particularly adapted for use inthe formation of catheters of this type, although it is to be understoodthat this device will have other applications which are obvious to thoseskilled in the art. However, for convenience, the device of thisinvention will be described hereinafter as the samewould be used for thefabrication of fine diameter catheters.

It is a primary object of this invention to provide a free running drawchuck which is particularly valuable where other constraints prohibitthe use of ordinary live-centers and follow-rests.

A further object of this invention is the provision of a free runningdraw chuck which permits high-speed rotation of a relatively thin,elongated, flexible workpiece in a lathe, while the workpiece ismaintained under substantial tension to preclude whipping of the same.

Another object of this invention is to provide a free running draw chuckwhich is readily adaptable for use with machine lathe tools havingtailstock spindles of different dimensions.

Still another object of this invention is the provision of a device ofthe type described which is simple and inexpensive to manufacture andmaintain, sturdy and durable in construction, and highly reliable inuse.

Other and further objects reside in the combination of elements,arrangement of parts and features of construction, all of which will beobvious from the following detailed description, which makes referenceto the accompanying drawing, wherein:

FIG. 1 is a schematic elevational view of a device according to thisinvention, showing the manner in which the same would be associated witha machine lathe tool;

FIG. 2 is an enlarged exploded view of the free running draw chuck ofthis invention, in cross section, showing the manner in which the sameis secured to a tailstock spindle of a lathe and also showing aconventional jaw means to be associated therewith; and

FIG. 3 is a fragmentary view, partly in elevation and partly broken awayfor illustrative clarity, illustrating a catheter that may be fabricatedutilizing the device of this invention.

Like reference characters refer to like parts throughout the severalviews of the drawing.

Referring now to the drawing, and particularly H6. 1, portions of aconventional machine lathe tool are designated generally by thereference numeral 10, with the rotatable headstock thereof beingdesignated generally by the reference numeral 12, and a fixed tailstockspindle of the conventional tailstock being designated generally by thereference numeral 14. The free running draw chuck of this invention isshown as secured to the tailstock spindle l4 and is designated generallyby the reference numeral 15. A conventional jaw means, such as a Jacobchuck is designated generally by the reference numeral l6, and arelatively thin, elongated workpiece in the form of a flexible metalwire 18 is shown secured between the headstock l2 and the jaw means 16.

By reference to H6. 2, details of the free running draw chuck 15 of theinstant invention will now be seen. The device 15 includes casing means20 having a tubular portion 22 and a front face portion 24 whichtogether define an interior chamber. A central aperture 26 is formedthrough the front face portion 24 and communicates with the interiorchamber.

A shaft member designated generally by the reference numeral 28 includesa front end portion 30 rotatably supported within the aperture 26 withterminal portions 32 extending beyond the aperture 26 to the exterior ofthe casing means 20. The terminal portions 32 are threaded forassociation with internally threaded portions 34 of the jaw means 16 ina wellknown manner. The shaft member 28 includes rear end portions 36which are located within the chamber in spaced relation to the interiorof the front face portion 24 of the casing means 20. Fixed to the rearend portions 36 of the shaft member 28 is a transversely extendingflange means 38 which is larger than the aperture 26 but smaller thanthe interior of the tubular portion 22 of the casing means 20.

Thrust bearing means, designated generally by the reference numeral 40,are carried within the chamber and operatively positioned between theinterior of the front face portion 24 of the casing means 20 and theflange means 38 of the shaft member 28. The thrust bearing means 40 maybe ball bearing means as shown. Suitable thrust bearing means may beangular-contact-type thrust bearings such as Fafnir bearing No. 7203W SUas shown in the Fafnir Service Catalog No. [9, Sixth Edition, of Sept.1958. As will be seen, preferably a pair of such thrust bearing means isused, the inner races 42 of which surroundingly engage the shaft member28 between the interior of the front face portion 24 of the casing means20 and the flange means 38 of the shaft member 28, and the outer races44 of which engage the interior of the tubular portion 22 of the casingmeans 20.

Preferably, an end cap means 46 is fixed within the chamber of thecasing means 20, rearwardly of the flange means 38 of the shaft member28. To this end, a shoulder 48 is defined on the interior of the tubularportion 22 of the casing means 20 rearwardly of the flange means 38 ofthe shaft member 28 and edge portions of the front surface 50 of the endcap means 46 abuttingly engage the shoulder 48. The end cap means 46extends entirely across the chamber within the casing means 20 and anyconventional lubricating means, such as grease or the like, may becarried within the chamber between the interior of the front faceportion 24 of the casing means 20 and the front surface 50 of the endcap means 46.

The end cap means 46 includes peripheral portions 52 which are taperedinwardly and rearwardly from the front surface 50 thereof. A pluralityof end cap setscrew means (one of which is shown at 54 as illustrativein the drawing) are threadably secured in circumferentially spacedrelation through the tubular portion 22 of the casing means 20rearwardly of the shoulder 48. The terminal portions 56 of the end capsetscrew means 54 engage the tapered peripheral portions 52 of the endcap means 46, and due to the tapered nature of the peripheral portions52, function to urge the edge portions of the front surface 50 of theend cap means 46 forwardly into abutting engagement with the shoulder 48to thereby insure a seal which precludes escape of the lubricating meansfrom the portion of the chamber between the interior of the front faceportion 24 of the casing means 20 and the front surface 50 of the endcap means 46.

Since the tailstock spindle 14 of different lathes may have differentoutside diameters, a plurality of brass split bushing means 58 ofdifferent dimensions may be provided to surroundingly engage thetailstock spindle 14 within the portion of the chamber of the casingmeans 20 rearwardly of the end cap means 46. A plurality of tailstockspindle setscrew means (one of which is shown as illustrative at 60 inthe drawing) may be threadably secured in circumferentially spacedrelation through the tubular portion 22 of the casing means 20, theterminal portions 62 of the tailstock spindle setscrew means 60 engagingthe exterior of the bushing means 68 to press the same into securingrelationship with a tailstock spindle 14 of a lathe surrounded thereby.

The use and operation of the device 15 of the instant invention will nowbe readily understood. The casing means is secured to the fixedtailstock spindle 14 of a lathe through the intermediary of the bushingmeans 58 and the tailstock spindle setscrew means 60.

Any conventional jaw means 16, such as a Jacob chuck is threadablysecured to the terminal portions 32 of the shaft member 28 and anelongated workpiece 18 is then fixed between the headstock 12 of thelathe and the jaw means 16 in known manner. It is to be understood thatthe headstock 12 may be of any conventional form and is merely shownschematically in the drawing. Similarly, other jaw means may besubstituted for the Jacob chuck shown illustratively in the drawing.

The workpiece 18 is placed under tension between the headstock 12 andthe jaw means 16 in any conventional manner, and due to the use of thefree running draw chuck of this invention, the same may be rotated underhigh speed without whipping.

In the fabrication of a fine catheter, a portion of which is designatedgenerally by the reference numeral 70 in FIG. 3, the workpiece 18 may beused as a mandrel. With this arrangement, catheters having uniquefeatures not commonly available such as a wire reinforced wall as thinas 0.010 inches and in the range of 1 mm. internal diameter sizes can bemade. Specifically, a mandrel or workpiece 18 having an externaldiameter corresponding to the desired internal diameter of the catheter70 is held between the headstock l2 and the jaw means 16, while tensionis applied until the mandrel or workpiece shows no deviations when tumedat operating speeds. The workpiece 18 may then be coated with anelastomeric material, such as rubber polymer paste and cured to form aninner plastic tube 72. Wire reinforcement 74 is supplied by helicallywinding over the cured polymer with, for example, 302 stainless steelspring wire of 0.004 or 0.005 inch diameter at 80-l 10 winds per inch.The wire is subsequently coated with an elastomeric material 76 andcured thus confining the wire 74 between the layers 72, 76 of plastic.Upon completion of the fabrication, the finished catheter 70 may beremoved from the mandrel or workpiece 18 resulting in tubing with anaccuracy of :t 0.005 inches overall.

A wire-reinforced catheter of the type shown in FIG. 3 and of theillustrative dimensions set forth hereinabove cannot efficiently be madeby other known techniques. Conventional chucks are not capable ofoperating in a manner so as to maintain a flexible, fine wire such asthe workpiece 18 turning at high speeds without deviations. The abilityto confine a helical wire such as 74 in the catheter tube 70 preventskinking of the catheter while the inner and outer layers of plastic 72,76, respectively, preclude contact of the wire 74 with the body.

It will now be seen that there is herein provided an improved freerunning draw chuck which satisfies all the objectives of the instantinvention, and others, including many advantages of great practicalutility and commercial importance.

Accordingly, what is claimed is:

1. A free running draw chuck for use with a lathe having a rotatableheadstock and a tailstock including a fixed tailstock spindle,comprising casing means having an interior surface defining a chamber,said casing means including a generally tubular portion and a front faceportion on one end of said tubular portion, said front face portiondefining a central aperture therethrough, a shaft member including afront end portion rotatably supported within said aperture and includingterminal portionsextending beyond said aperture to the extenor of saidcasing means, and a rear end portion located within said chamber inspaced relation to the interior of said front face portion of saidcasing means, transversely extending flange means on said rear endportion of said shaft member, said flange means being larger than saidaperture and smaller than the interior of said tubular portion of saidcasing means, thrust bearing means within said chamber operativelypositioned between the interior of said front face portion of saidcasing means and said flange means of said shaft member to support saidshaft means for rotation relative to said casing means, means forsecuring said tubular portion of said casing means to the tailstockspindle of a lathe rearwardly of said flange means of said shaft member,and means for securing said terminal portions of said shaft member to ajaw means adapted to engage one end of a relatively thin, elongatedelement, the other end of which is rotatably carried by the headstock ofthe lathe, whereby the elongated element can be freely rotated relativeto the fixed tailstock spindle of the lathe while maintained undertension between the rotatable headstock and the jaw means.

2. The free running draw chuck of claim 1 wherein said tubular portionof said casing means includes a shoulder defined in its interiorrearwardly of said flange means of said shaft member, end cap meansextending transversely across said chamber and including a frontsurface, edge portions of which abuttingly engage said shoulder, wherebysaid shoulder precludes said end cap means from moving forwardly withinsaid chamber.

3. The free running draw chuck of claim 2 further including lubricatingmeans within said chamber between the interior of said front faceportion of said casing means and said front surface of said end capmeans.

4. The free running draw chuck of claim 2 wherein said end cap meansfurther includes peripheral portions tapered inwardly and rearwardlyfrom said front surface thereof, and end cap setscrew means threadablysecured in circumferentially spaced relation through said tubularportion of said casing means rearwardly of said shoulder, said end capsetscrew means having terminal portions engaging said tapered peripheralportions of said end cap means to urge said edge portions of said frontsurface of said end cap means forwardly into abutting engagement withsaid shoulder.

5. The free running draw chuck of claim 1 wherein said means forsecuring said terminal portions of said shaft member to a jaw meansincludes threaded means defined on said terminal portions.

6. The free running draw chuck of claim 1 wherein said means forsecuring said tubular portion of said casing means to the fixedtailstock spindle of a lathe includes tubular bushing means positionedrearwardly of said end cap means within said chamber, said bushing meansbeing adapted to surroundingly engage the fixed tailstock spindle of alathe, and tailstock spindle setscrew means threadably secured incircumferentially spaced relation through said tubular portion of saidcasing means, said tailstock spindle setscrew means having terminalportions engaging the exterior of said bushing means to press saidbushing means into securing relationship with a tailstock spindle of alathe surrounded thereby.

7. The free running draw chuck of claim 1, wherein said thrust bearingmeans includes ball bearings.

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1. A free running draw chuck for use with a lathe having a rotatableheadstock and a tailstock including a fixed tailstock spindle,comprising casing means having an interior surface defining a chamber,said casing means including a generally tubular portion and a front faceportion on one end of said tubular portion, said front face portiondefining a central aperture therethrough, a shaft member including afront end portion rotatably supported within said aperture and includingterminal portions extending beyond said aperture to the exterior of saidcasing means, and a rear end portion located within said chamber inspaced relation to the interior of said front face portion of saidcasing means, transversely extending flange means on said rear endportion of said shaft member, said flange means being larger than saidaperture and smaller than the interior of said tubular portion of saidcasing means, thrust bearing means within said chamber operativelypositioned between the interior of said front face portion of saidcasing means and said flange means of said shaft member to support saidshaft means for rotation relative to said casing means, means forsecuring said tubular portion of said casing means to the tailstockspindle of a lathe rearwardly of said flange means of said shaft member,and means for securing said terminal portions of said shaft member to ajaw means adapted to engage one end of a relatively thin, elongatedelement, the other end of which is rotatably carried by the headstock ofthe lathe, whereby the elongated element can be freely rotated relativeto the fixed tailstock spindle of the lathe while maintained undertension between the rotatable headstock and the jaw means.
 2. The freerunning draw chuck of claim 1 wherein said tubular portion of saidcasing means includes a shoulder defined in its interior rearwardly ofsaid flange means of said shaft member, end cap means extendingtransversely across said chamber and including a front surface, edgeportions of which abuttingly engage said shoulder, whereby said shoulderprecludes said end cap means from moving forwardly within said chamber.3. The free running draw chuck of claim 2 further including lubricatingmeans within said chamber between the interior of said front faceportion of said casing means and said front surface of said end capmeans.
 4. The free running draw chuck of claim 2 wherein said end capmeans further includes peripheral portions tapered inwardly andrearwardly from said front surface thereof, and end cap setscrew meansthreadably secured in circumferentially spaced relation through saidtubular portion of said casing means rearwardly of said shoulder, saidend cap setscrew means having terminal portions engaging said taperedperipheral portions of said end cap means to urge said edge portions ofsaid front surface of said end cap means forwardly into abuttingengagement with said shoulder.
 5. The free running draw chuck of claim 1wherein said means for securing said terminal portions of said shaftmember to a jaw means includes threaded means defined on said terminalportions.
 6. The free running draw chuck of claim 1 wherein said meansfor securing said tubular portion of said casing means to the fixedtailstock spindle of a lathe includes tubular bushing means positionedrearwardly of said end cap means within said chamber, said bushing meansbeing adapted to surroundingly engage the fixed tailstock spindle of alathe, and tailstock spindle setscrew means threadably secured incircumferentially spaced relation through said tubular portion of saidcasing means, said tailstock spindle setscrew means having terminalportions engaging the exterior of said bushing means to press saidbushing means into securing relationship with a tailstock spindle of alathe surrounded thereby.
 7. The free running draw chuck of claim 1,wherein said thrust bearing means includes ball bearings.